Means for impressing periodically-varying electric currents upon telegraph or other circuits



No. 704,930. Patented July'lfi, I902.

H.-1\ ROWLAND, Decd. u, H. RDWLAND. Admi niatratrix; MEANS FOR IHPRESSING PERIODICALLY VARYING ELECTRIC GUBRENTS UPON T EG APH on OTHER cm cuns.

Application fild Dec. 11, 1901.

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UNITED STATES PAT NT OFFICE.

HENRIETTA H. ROW'LAND, OF BALTIMORE, MARYEAND, ADMINISTRATRIX OF HENRY AUGUSTUS ROWLAND, DECEASED, ASSIGNOR TO ROWLAND TELEGRAPHIC COMPANY, OF BALTIMORE, MARYLAND, A CORP CRATION OF NEW JERSEY.

MEANS FOR IMPRESSING PERlODlCALLY-VARYING ELECTRlC CURRENTS UPON TELEGRAPH OR OTHER CIRCUITS.

SPECIFICATION forming part Of LettersPatent NO. 704,930, dated July 15,1902. Original application filed July 24, 1901, $erial No. 69,524. Divided and this application filed December 11, 1901. Serial No. 85,618. (No mitten:

To all whom it may concern:

Be it known that HENRY A. ROWLAND, decleased, late acitizen of the United States, and a resident of Baltimore city, in theState of 5 Maryland, did invent certain new and useful Improvements in Means for Impressin g a Periodically-Varying ElectricOurrent upon a Telegraph or other Circuit, (Case J, )of which the followin g is a full, clear, and exact descrip- IO tion, such as will enable any one skilled in the art to which it appertains to make and use the same.

.This invention relates to improvements in means for impressing an alternating or other periodically-varying electric current upon a telegraph or other electric circuit.

The said inventionconsists, further, in the employment of this meansin the operation of duplex telegraph-lines. In working a telegraph-line duplex it is generally necessary to locate'at each end of l the line a source of signaling-current to operate the receiving-relay or other main-line instrument at the distant end, and when these sources of signaling-current are alternating-current dynamos this necessitates the employment of a dynamo at each end of the duplex line. The present invention,however, contemplates the employment of means whereby either one or both of these dynamos may be done away with and the signaling-current derived from a circuit in which the current is relayed from a source of direct current.

The present application constitutes a division of the application for improvements in telegraphic distribution, Serial No. 69,524, filed by Henrietta H. Rowland, administratrix of the estate of Henry A. Rowland, deceased, July 24,1901. I

In order to morefully describe the said invention,, reference will be had to the accompanying'drawings, in which a Figure 1 isa diagram illustrating the principle of the'said invention, and'Figs. 2, 3, and

.45 4: are diagrams illustrating alternative ways of connecting the pole-changer shown on the right of Fig. 1.

Similar letters and numerals refer to similar parts throughout the several views.

Referring first to Fig. l, L represents a duplex telegraph-line; A,. an alternating-current dynamo located at one end of said line and delivering its current thereto; B and B, main-line transmitters; Cand C, main-line relays, and D and D artificial lines. At the right-hand end of the line in the drawings the contact of the transmitter B instead of passing to a dynamo, as at the other end of the line, passes to the secondary of a transformer E, the. other terminal of the said secondary being grounded, as shown. One terminal of i the primary of this transformer is connected by wire 1 to a point 2 intermediate between two condensers F F, connected across the terminals of a source of constant-potential local current. The other terminal of the primary of this transformer is connected, as by wire 3, to a brush 9 of the pole-changer G. This brush g is intermediate between two brushes g and 9 the former of which connects through a resistance 4 to the negative pole of the local current-supply and the latter through a similar resistance 5 to the positive pole. This pole-changer comprises two crownsections 9 and g", which interlock, as shown. The brushes g and g are constantly in contact, respectively, with the sections ,9 and g, while the brushg'passes from one section to the next as the pole-changer rotates. This pole-changer maybe driven in any desired manner, and as it rotates beneath the brushes g, g, andg an alternating current will be sent through the primary of the transformer E as the condensers F F are alternately charged and discharged. For example, in the position of the pole changer brushes shown in Fig. 1 the condenser F on the left will send a positive charge through the primary of the said transformer, and when the brush g ispassed on to the next segment of c the pole-changer the'condenserli on the right will discharge and send a negative charge through the said transformer, inducing an alternating current in the secondary,which is connected in series with the line L. In this way an alternating current derived from a source of constant-potential current is impressed upon the line Land is of afrequency dependent upon the rapidity of the rotation of the pole-changer. This pole-changer may be driven in synchronism with the dynamo or other generating device at the other end of the line by mounting it upon the shaft with or otherwise gearing it to a synchronizer H, comprising a small motor regulated by an alternating current and driven by an independent source of power, substantially as shown and described in Letters Patent No. 622,636, granted to Henry A. Rowland April 24, 1898. For the purpose of obtaining an alternating current for regulating this synchronizer H which shall bear a fixed phase relation to the line-current two condensers F F maybe-connected across the terminals of the constant-potential-current supply and one terminal of the regulatingcoils of the synchronizer connected, as by wire ,6, to a point intermediate between these condensers and connecting the other terminal of said coils to the tongue of the relay 0'.

1 arrangement.

The pole-changer G may be of any desired form. For example, this pole-changer may be simply a relay in which the wire 3 connects to the tongue and the wires which lead to the brushes 9 and g connect to the tonguecontacts, the equivalency of these two devices being obvious. Moreover, the arrangement of connections and apparatusindicated on the right of the line in Fig. 1 may be also located at the left-hand end of the line, in which case no alternating-current dynamo would be employed at all.

While the local alternating or periodicallyvarying current is derived in the arrangement shown in Fig. 1 by the alternate charging and discharging of condensers, the invention is by no means-confined to this specific For example, Fig. 2 shows an arrangement by which the condensers F F are replaced by resistances R R, connected across the terminals of the source of local potential current of, for example, one hundred and ten volts.

In the arrangement of sections shown in Fig. 3 the current is derived from split battery K, while in Fig. 4 the local current source is represented as being that of an Edison three-wire circuit. Furthermore, in some cases it may not be necessary to employ a transformer, in which event the wires 1 and 3 would be connected in series with the main line; but wherever the line is of considerable length the employment of transformers, as shown, is to be preferred.

Having thus described the said invention, what is claimed, and desired to be secured by Letters Patent of the United States, is

1. The combination of a source of direct electric current and means for producing a periodically-varying current from said direct current, an electric circuit, and a transformer by which said periodically-varying current is impressed upon said electric circuit.

2. The combination with an electric circuit, of a source of periodically-varying electric current located at one end of said circuit and delivering thereto a normally continuous current, a source of direct current located at the other end of said circuit, a current-changing device operated in synchronism with the said periodically-varying current and producing a periodically varying current from said source of direct current, and means for impressing the current derived from said source of direct current upon the said circuit.

3. In a telegraph-line, the combination of a transformer located in the main-line circuit, means for producing a periodically-varying current from a source of direct current connected to the primary of said transformer, and means for impressing said periodicallyvarying current upon the line.

4. In a duplex telegraphline, the combination of a transformer located in the main-line circuit, means for producing a periodicallyvarying current from a source of direct current connected to the primary of said transformer, and means for impressing said periodically varying current upon the duplex line.

5. The combination, in a duplex telegraphline, of a source of direct electric current, means for producing a periodically-varying electric current from said direct current and a transformer by which said periodically-varying current is impressed. upon the duplex line.

6. In a duplex line, the combination with an alternating-current dynamo located at one end of said line, and supplying current thereto, of a source of direct current located at the other end of said line, a pole-changer, a .circuit in which the direction of the current is varied by said pole-changer and in which the current is derived from said source of direct current, and means for impressing the periodically-varying current produced by this device upon the main line.

7. In a duplex telegraph-line, the combination with a dynamo-electric machine located at one end of said line and delivering a normally continuous alternating current thereto, of a transformer located in the main-line circuit at the other end of said line, means for producing a periodically-varying electric cur rent from a source of direct current connected to the primary of said transformer, and means for impressing said periodically-varying current upon the duplex line.

8. In a duplex telegraph-line, the combination with a dynamo-electric machine located at one end of said line and supplying current thereto, of a circuit located at the other end of said line in which a periodically-varying current is derived from a source of direct-current supply, a transformer receiving current from said circuit, and the said transformer impressing upon the said line the current induced in it from said circuit.

9. In aduplex telegraph-line, the combination with asonrce of periodically-varying electric current located at one end of said line, of a duplex transmitter located at the other end of said line, a transformer having its secondary connected in series with the main-line circuit, a source of direct current, a circuit in which a periodically-varying current is produced from said direct current, a currentchanging device for producing said periodically-varying current, said circuit being connected to the primary of said transformer and a synchronizer operating in synchron ism with the periodicailyvarying current from the other end of the line and driving said currentchanging device.

10. In a duplex telegraph-line, the combination with an alternating-current dynamoelectric machine located at one end of said line and delivering current thereto, a source of direct current located at the other end of said line, a synchronizer rotating in synchronism with saidrdynamo-eiectric machine, a current-changing commutator driven by said synchronizer, a local circuit deriving current from said source of direct current and in which the direction of the current is periodically varied by said current-changer, and a transformer having its primary connected in the circuit of said current-changer and its secondary in the main line.

In testimony whereof I afiix my signature in the presence of two witnesses.

HENRIETTA H. ROWLAND,

Adminisimtr'iw of the estate of Henry A. R0w 

